Why does my faucet/shower leak? Most of the time a two or three handle shower valve uses a basic stem and seat. The operation of a two or three handle valve is not complex at all. The picture below this text will be used to explain how this valve operates and how to fix your problem. If you take a look at this common stem you will notice part “B” this is the actual stem. Normally the stem has threads towards the bottom of the unit, here it is labeled “D”. The threads on the stem move inside the threads on the inside of the stem housing “G”. This causes the stem to move in and out. When you turn off the faucet the stem moves in, which makes a seal at the bottom of the stem “E”. The part labeled “E” is the washer on the bottom of the stem. It makes contact with part “F” the seat. The bottom of the stem (the washer) and the seat are the only two parts which control water flow and the on/off operation. The rest of the stem is used to reach outside the wall to your handle. The rest of the stem housing is used to hold the stem in place and allow the turning motion. Part “C” is called the bonnet. The bonnet is used to prevent any water from exiting the stem body into the handle area. Stem Most of the time the only thing wrong with your shower or lavatory valve is that the stem, washer and the seat need to be replaced. To do this you will need a stem removal socket, a seat wrench, and a fillips screw driver. Remove the handle and the trim pieces. Then use the stem removal socket to remove the entire unit. Put the seat wrench down into the opening to remove the stem. Some valves are ceramic which do not require seats and some other valves use a different type of washer/stem seal. If your stem does not look like this, is ceramic or if you need further help please call or e-mail. NOTE: Be sure to put the stem in the open position before removing or replacing the unit back into the valve body. If the stem is left in the closed position it can destroy your stem, washer, and/or seat.